(1) Field of the Invention
This invention relates to substrate treating apparatus for treating substrates such as semiconductor wafers and substrates for liquid crystal displays (hereinafter simply called substrates) by immersing the substrates in a treating solution stored in a treating tank.
(2) Description of the Related Art
A conventional apparatus of this type includes a plurality of spherical bubblers arranged in the bottom of the treating tank storing a treating solution. The bubbles are arranged in the direction of arrangement of a plurality of substrates under treatment (see Japanese Patent Publication No. 8-2419 (1998), for example).
FIG. 1 refers. FIG. 1 is a side view showing an outline of a conventional apparatus.
This apparatus includes a plurality of bubblers 101 arranged in the bottom of a treating tank 102. The bubblers 101 are arranged at fixed intervals in the direction of arrangement of a plurality of wafers W (i.e. the transverse direction in FIG. 1). The wafers W are held in upstanding posture by a vertically movable back plate 103 and support members 105 extending horizontally from lower positions of the back plate 103. A positional relationship between these elements is determined such that all the wafers W are enveloped in bubbles emerging and spreading upward from the bubblers 101.
Specific types of treatment performed by such an apparatus include cleaning, etching, stripping, particle removal and metal removal. More particularly, for example, sulfuric acid is used as a treating solution and heated to 120 to 130° C. or higher. Then, ozone gas is injected into the treating solution, and wafers W are immersed therein. At this time, a strong oxidizing substance such as peroxodisulfuric acid synthesized by sulfuric acid and ozone dissolves or strips off unwanted film such as resist film on the surfaces of wafers W.
The conventional apparatus noted above has the following drawbacks.
The conventional apparatus is slower in treating wafers W located in opposite end regions (region “a” and region “b” in FIG. 1) in the direction of arrangement of the plurality of wafers W than in treating the other wafers W located at and adjacent the middle. Thus, it is difficult to treat all the wafers W uniformly.
Further, the conventional apparatus has the bubblers 101 spaced from one another in the direction of arrangement of the wafers W. This results in different conditions in which the bubbles contact and act on the wafers W located right above the bubblers 101 and the wafers W located right above the spaces between the bubblers 101. Thus, the conventional apparatus has difficulties in treating all the wafers W uniformly.